Design High Precision Orbit Extrapolation Algorithm For Mars Detector

With the development of space technology,deep space exploration has become an international research hotspot,the level of deep space exploration and space activities has become a sign of national comprehensive force,mars exploration is the focus of deep space exploration.In the deep space exploration mission,orbit extrapolation is always involved in the process of optimizing and refining the entire orbit.The extrapolation accuracy of orbit directly affects the orbital optimization process and orbit determination accuracy.Therefore,the improvement of orbit extrapolation accuracy is of great significance for the Mars detectors to reach Mars accurately.Firstly,this paper describes the time system,the coordinate system,and star calendar of related objects associated with the Mars mission,and describes the classical orbital root knowledge of the detector motion state.And then analyzes the influence of three kinds of perturbation force models around the earth,around the sun and around Mars on the extrapolation accuracy of the detector's orbit.Secondly,according to the two-body problem and the Lambert problem,the direct transfer orbit of the Mars detector is designed,the earth launched orbit is designed by the method of conic section stitching,the elliptical orbit is designed by mechanics knowledge and Kepler's law.Then,the orbit and position information of Mars detector are obtained by STK software.The results provide the simulation data and environment for the track extrapolation test.Finally,numerical integration method and geometric method are used to orbit extrapolation.In the aspect of numerical integration method of orbit extrapolation,in view of the fact that the variable step algorithm in the numerical integration method can not only improve the accuracy of the track extrapolation,but also reduce the computational complexity and improve the efficiency of the calculation.This paper proposes a new variable step size algorithm--The depth of the path is controlled by the area of the detector's flight arc and the center of the body Constitution.It is known that this algorithm is suitable for both circular and elliptical orbits.In the aspect of the geometric method of orbital extrapolation,the factors affecting extrapolation accuracy are analyzed in this paper.After studying the influence of the fitting order and the number of fitting points on the extrapolation accuracy and fitting precision,in order to solve the problem that the extrapolation accuracy of the existing geometrical method is affected by the number of fitting orders and the number of fitting points and the extrapolation error is very large.In this paper,the existing Chebyshev polynomial fitting method is improved-two iterations of Chebyshev polynomial.In the aspect of numerical integration method,The simulation results show that the variable step size algorithm proposed in this paper not only improves the extrapolation accuracy,but also applies to deep space exploration and for a month orbit extrapolation.In the aspect of the geometric method,The simulation results show that the improved algorithm of chebyshev can effectively reduce the influence of the fitting order and the number of fitting points on the extrapolation accuracy and improve the extrapolation accuracy of the track.It is suitable for the accurate perturbation model cannot be established and within 15 minutes orbit extrapolation.